A Circularly Polarized Low-Cost IoT Electrically Small Antenna

A Circularly Polarized (CP) Electrically Small An-tenna (ESA) is presented targeting low data-rate IoT applications. The antenna is based on a combination of a capacitively-loaded magnetic dipole generating a horizontally polarized field and a top-loaded electric dipole generating the vertically polarized orthogonal component. The antenna has an electrical size of 0.58rad at 2.48GHz. Its radiation pattern is omni-directional in the azimuth plane with a left-hand CP realized gain of -4.7dBi, an axial ratio lower than 3dB and a total radiation efficiency of 41%. This makes it suitable for use with the circuitry of IoT terminals that require 360 degrees spatial coverage with immunity to multi-path and polarization mismatch effects.